Loop-takers for sewing machines



June 30, 1959v T. J. ZYLBERT LOOP-TAKERS FOR SEWING MACHINES 2 Shets-Sheet 1 Filed Feb. 25. 1955 INVENTOR Thaabeus J Zy/bert BY WITNESS June 30, 1959 T. J. ZYLBERT LOOP TAKERS FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed Feb. 25, 1955 7 ATTORNEY mm m z W =T m Q United States Patent LOOP-TAKERS FOR SEWENG MACHINES- Thaddeus J. Zylhert, South Plainfield, N.J., assignor to TheSinger Manufacturing Company, Elizabeth, N.J., a corporation. of New Jersey Application February 25, 1955, Serial No. 490,467

7 Claims. (Cl. 112-231) The. present invention. relates to sewing machines and hasfor' a primary object toprovide a new and improved loopetaker' for sewing machines. It is a specific object of: this invention to provide means for precluding the formulation of so-called. hitch-stitches, which is defective sewing wherein the needle-thread is knotted about the bobbin-thread instead of merely looped about the same as in the formation of so-called perfect lock-stitches.

Having in mind the aboveand. other objects that will be evident from an understanding of this disclosure, the invention: comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred: embodiment of the invention which is hereinafter set forth in such detail as'to enable those skilled in the art: readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying, drawings in which;

Fig; 1. isaa top plan view ofa rotary hook, for a sewing machine embodying the present invention, the hook being illustratedper'se except for the, cooperating needles which are in section and the hook-shaft which is broken away, and the sewing threads are illustrated schematically to show the functional cooperation of the various elements of. the hook during sewing.

Fig. 2 is a front elevation view of the hook as illustratcd in Fig. l but also including a fragmentary portion in: elevation of the needles and afragmentary portionin section of the throat-plate andwork.

Figs. 3' and 4 areviews similar to Fig. 2but illustrating the. relationship of the stitching means and the'sewingthreads at'subsequent'points in the cycle of stitch formation and, for clarity, omitting'thedetailed showingof the bobbin-case.

Fig. 5 is: a diagrammatic view in: perspective of the threadrconcatenation in a seamformed by the hookand cooperating elements of. Fig. 1.

Fig. 6-is; aside elevation view of-the bobbin-case-carrier perse illustrated in Fig. 1.

Figs. 7, 8;, 9, 1.0and 11 are views corresponding respectively to- Figs. 1,, 2, 3, 4 and 5, but illustrating the prior art construction and thestitch formation thereof.

With. reference to. Figs. 7 and 8 there is illustrated a prior art constructionof a rotary hook for a sewing machine,- which hook issubstantially as disclosed in the Kessl'ei: patent,-No. 2,085,699, t'o which reference may be had for a detailed description of the. construction and operation thereof. Briefly, this device includes a cupshapedliook-body I mounted upon a rotating hook-shaft 2' and having a loop-seizing beak 3 formed integrally in the cylindrical side-wall of the hook-body adjacent the gap .at the discontinuous portion therein. The side-Wall of thel'hook body is formed with an internal raceway'in which is journaled the peripheral bearing rib 4 of a bobbin-case-carrier 5 that carries a bobbin-case 6 and a bobbin-7, the usual bobbin-threadtension spring 6 being secured to the periphery of the bobbin-case 6. In the usual-fashion during operation the bobbin-case-carrier 5 is held stationary whilethe hook-body 1 is rotated thereabout; The bearing rib 4 is discontinuous to provide a loop-detaining shoulder 8 and a loop-confining shoulder 9. The raceway in the hook-body 1 includes an opensided portion. that is closed by a gib 10 having a loop-controlling tail 11' extending into the gapformed at the discontinuous portion of the side-Wall of the hook-body 1. A plate 12 is also secured to the periphery of the hookbody, the plate 12' having a needle-thread deflecting beak 13 at one end which extends into the gap in the side-wall of the hook-body adjacent to but spaced from the loopseizing beak 3, and a bobbin-thread pull-off flange 14.

As illustrated, the hook is designed to cooperate with a pair of needles including a left-hand needle 15 and a right-hand needle 16, which needles are reciprocableto a position in which they extend downwardly through the work W and the throat-plate 17 of the machine into cooperation, with the hook. In the usual fashion, each needle penetrates the work and then, as it iswithdrawn, throws a loop of thread which is seized by the beak 3 of the hook-body, 1, expanded, cast about the lower thread mass WhlChlS wound upon the bobbin 7, and then with drawn. In the drawings, the bobbin-thread is designated 18, the needle-thread ofthe left-hand needle 15 is designated;1-9' and'the needle-thread of the right-hand needle 16 is designated 20.

The illustrated, rotary hook is designed for use inv a sewing machine; such as disclosed, for example, in the Eames patent, No. 2,024,434, i.e., it is designed to be arranged on a horizontal axis transversely of the bed of the machine or, what is the same thing, parallel to the line of. feed or the line of stitch or seam formation, whereby it may cooperate with a laterally vibrating or, as more commonly called, a zigzag needle. As seen in Fig. 8, thehook rotates counterclockwise in the direc tion of the arrow A, and, as seen in Fig. 7, the direction of feed of the work is to the rear axially of the hook as designated-by the arrow B.

There has always been a problem in the sewing ma-. chine art, of producing so-called perfect lock-stitches rather than fhitch stitches. The problem was recognized. and discussed, for example, in each of the follow ing patents, Hemleb, No. 1,877,757; Grieb, No. 1,988,; 789; and Parry, No. 2,327,817. A. considerable amount of study has been given to this problem but the range of, feeding radially from the point of stitch formation in. which. hitch-stitches rather than lock-stitches will. be formed, is still determined primarilyv by actual. sewing tests. It is understood, of course, that feeding may be forward. or reverse, asin straight stitching and back-tacking, or laterally to the side at any. angle relative to the; point of stitch. formation as in embroidery work or sig nature stitching.

The problemof hitch-stitches is also present in zigzag sewing in which the relative position of the needle and loop-taker at loop-seizure is variable. As noted below, the problem has also been found to exist in the use of twin-needles such as disclosed in the patent application of Platt, Serial No. 466,991, filed Nov. 5, 1954, now

Patent No. 2,722,904, dated Nov. 8, 1955. For pur-.

poses of illustration, the present invention is herein dis:

closed as it relates to the problem of the formation. of

hitch-stitches, as, distinguished from, perfect lock-stitches, in the use of-a twin-needle.

As seen in Figs. 7 and 8, the illustrated hook rotates lock-stitches, whereas the left-hand needle 15 will form' This has been illustrated in Figs. 8, 9; and 10. Following first the right-hand needle 16 and its' hitch-stitches.

thread 20, the loop-seizing beak passes to the rear of 3 the needle 16, as seen in Fig. 8, or on the short groove side of the needle, and is travelling counterclockwise. In Fig. 8, the point in the stitching cycle that is illustrated is shortly beyond loop seizure. The supply limb of the thread 20 extends from the supply through the thread handling devices of the machine down the needle, through the eye thereof and beneath the loop-seizing beak of the hook in front of the loop-detaining shoulder 8. The worklimb of the thread extends from beneath the loop-seizing beak 3 of the hook around the rear edge of the beak, forwardly in the slot between the beak 3 and the beak 13 of the plate 12 and then upwardly through the needlehole in the throat-plate 17 to the previous stitch in the work W. The loop in the thread 20 is completely behind the lead of the bobbin thread 18 to the work W. As the hook continues to rotate, the loop of needle-thread is pulled back on the beak 3 and thereby expanded. That portion of the thread on the underside of the beak 3 is caught on the loop-detaining shoulder 8. Thereafter, the supply limb of the thread extends from the supply through the work, rearwardly on the periphery of the bobbin-case-carrier to the slot between the beak 3 of the hook and the beak 13 of the plate 12. The work-limb of the thread extends from this slot upwardly to the last stitch set in the work.

Until cast off, the supply-limb and the work-limb of the thread lie on the periphery of the bobbin-case-carrier 5. At cast-off, which is slightly beyond the position illustrated in Fig. 9, the two limbs slide from the periphery of the bobbin-case-carrier and start sliding laterally relative to the hook, the work-limb sliding across the face of the carrier 5 and the bobbin-case 6 and the supplylimb sliding across the rear of the carrier 5 or between the rear of the carrier 5 and the bottom of the hook-body 1. As rotation of the hook proceeds, the thread that has been provided in the system for the expansion of the loop so that it can be thrown around the bobbin, is taken up, the loop sliding from the slot between the beaks 3 and 13 and onto the loop-controlling tail 11, and away from the loop-detaining shoulder 8 toward the loop-confining shoulder 9. The thread limb in back of the bobbin-casecarrier 5 escapes or is pulled out by the take-up when the discontinuous portion of the raceway adjacent the tail 11 passes the loop-confining shoulder 9 of the raceway. This portion of the cycle is substantially as illustrated in Fig. 10, although somewhat exaggerated to illustrate the relationship of the thread leads relative to the bobbinthread 18.

As will be seen from Fig. 10, the thread 20 has formed with relation to the bobbin thread 18, a lock-stitch, i.e., the work limb of the thread leads down from the previous stitch in the work, around the bobbin-thread, and into the supply limb of the thread which leads upwardly to the supply. The completed stitch is illustrated in Figs. 7 and 11.

With reference to the lefthand needle 15 and its thread 19, the stitch forming cycle is exactly the same as with the needle 16 and thread 20 except for the lead of the bobbin-thread 18 with relation to the needle. When sewing with twin-needles, the bobbin-thread, which is concatenated with both needles-threads, lies on the underside of the work along a line that is between the two lines defined by the needle-threads 19 and 20. The

lead of the bobbin-thread is from the bobbin-thread tension 6 over the face of the bobbin-case-carrier 5 and upwardly and rearwardly to the last stitch in the work. This brings the bobbin-thread lead between the two needles 15 and 16 as can best be seen from Figs. 7 and 8. The right-hand needle 16 descends to the right of the lead of bobbin-thread from the bobbin 7 to the last stitch in the work and, as above pointed out, this produces a lock-stitch. The left-hand needle 15 descends to the left of the bobbin-thread lead and, by following the thread 19in Figs. 8, 9 and as it is expanded, thrown about the bobbin, and withdrawn, in the same manner as was done for the thread 20, it will be seen that the resulting concatenation of threads is a hitch-stitch and not a lock-stitch. The work limb of the thread 19 leads down from the work, completely about the bobbinthread, and into the supply limb of the thread which rises between the bobbin-thread and the work limb of the needle-thread. This stitch, which actually consists of knotting the thread, can be best seen in Figs. 7 and 11.

With the readily available left twist threads in both needles 15 and 16, the right-hand needle 16, which forms lock-stitches, will twist the thread further or tighten the twist thereof and the left-hand needle 15 which forms hitch-stitches will untwist the thread and thus unravel it.

The net result of sewing with twin-needles is that the right-hand seam will consist of lock-stitches and the left-hand seam will consist of hitch-stitches. Of more importance than the fact the hitch-stitches are inferior in appearance and strength, is the fact that during sewing and untwisting of theleft-hand thread 19 is cumulative and finally the thread becomes frayed and eventually the loop-seizing beak of the hook catches only a few strands of the thread and breaks them. The broken strands are thereafter stripped back from the unbroken strands by the needle as the thread is passed back and forth through the eye thereof. The thread which is thus weakened will break shortly thereafter. In practice, it has been found that sewing will progress with a setting of about 8 stitches per inch for a distance of only about eight or ten inches before the thread breaks.

This thread breakage can be remedied by using right twist thread in the left-hand needle 15, but this practice has many disadvantages, i.e., the use of two different types of thread considerably complicates the problem of keeping them separate and selecting the proper thread for each needle, the right twist thread is not readily obtainable and, finally, even though the thread will not break because of fraying, the stitch formation is still of undesirable hitch-stitches.

It is possible to overcome the formation of hitchstitches in the left-hand needle 15 by controlling the lead of the bobbin-thread so that it will be presented to this needle in the same manner as it is presented to the right-hand needle 16. Specifically, this is done by leading the bobbin-thread to the rear of the path of needle reciprocation as seen in the drawings. This expedient is in itself not new. For example, reference is made to the copending application of R. E. Johnson, Serial No. 471,766, filed November 29, 1954, wherein there is disclosed and claimed a throat-plate having a bobbin-thread directing boss formed upon the underside thereof. The above noted patent of Grieb shows a bobbin-case having a thread-delivery eye located in the face thereof. In the above noted patent of Parry there is provided a plate secured to the face of the bobbin-case for lateral adjustment, the plate having a thread-guiding slot therein. The present invention is directed to a new and improved means for controlling the lead of a bobbin-thread relative to the needle to avoid the formation of hitch-stitches, which at the same time will provide various other advantages as hereinafter set forth.

The invention is disclosed in Figs. 1-6 in which the variouselements of the device are designated by the same reference numerals as the corresponding elements of the device as disclosed in Figs. 7-11. In accordance with the invention, there is provided on the cast-on side of the bobbin-casecarrier' a slot 21 in the cylindrical side-wall cf the bobbin-case-carrier 5, as can be seen in Fig. 6. The slot 21 opens at the edge 22 defined by the usual gap in the side-wall of the carrier 5 that is provided to accommodate the bobbin-thread tension spring 6 and its-securing means, the other edge of the gap being designated 23. The slot 21 extends into the side-wall of'the carrier 5 from the edge 22 from a point adjacent the bearing rib 4 and in a direction diverging with relation to the bearing rib. The slot 21 terminates. in what is termed a thread-delivery eye 24 disposed on. the. periphery of; the bobbin-case-carrier at a. point on the cast-on sid'e thereof or, in. other words, beyond the path of. needle reciprocation. in, the direction of rotation. of said hook and to laterally ofv a notch 25' which notch. 25 is theusual rotation-restraining notch designed to receive arotation-rest'raining finger (not shown). To facilitate threading, the mouth of the slot 21 is enlarged, as at 26. Thebobbin-case-carrier 5 also includes the usual needle-thread .loop-controlling, flange 27 on the cast-off side thereof. The bottom of the bobbin-casecarrier 5 isdesignat'ed- 28, and the top, which is hereinafter termed the free edge, is designated 29.

As seen.in"Figs. 1 and 2", the thread-delivery eye 24 is disposed tojthe' left. of the path of reciprocation of the needles 15 and 16 at a point. on the periphery of the bobbin-case-carrier 5. The bobbin-thread 18, as it emergestfromibeneath the end ofthe. tension spring 6 is di'rectedithrough the thread-delivery eye 24, the. threading of'which is facilitatedby 'the slot 21, and then runs to the'last'stitch set'irrthe work. Of course, the bobbinthread 1 8".will' during sewing" still form along a line disposed between the lines: defined" by' the two needlethreads- 19 and 2.0i However, because of the threaddelivery"eye"24,,the leadofthe bobbin-thread will not pass: between the paths. of reciprocation. of the. needles 15f and 16, butrather will" pass to the rear of. both oftlie m-Csee Figs; 1" andZ), With reference to Figs. 2,; 3 and4'; it Wilk'bfi seen "byfollowing the thread concatenations fronr lo'opf seizure through cast-off until the thread escapes from the hook, that there is formed lockstitches in bothof the'threads I9 and 2'0 whereas with the construction' as illustrated in Figs; 7'-1l there was formeda hitch-stitchinthel'eft-hand needle=thread 19.

The thread directing" means in accordance with this invention thus comprises a very simple expedient involvinginstead of added parts, only the thread-eye 24 in the side-wall of the bobbin-case-carrier. Besides being very economical the present-invention is also very efiicient in that thereis substantially nopossibilitythat the bobbin-thread may become misdirected in such a manner as to form hitch-stitches with the needle-thread 19 since the bobbimthread' is firmly controlled bythe threadeye 24.

In addition to the above, there are various other advantages derived by-theuse ofa guided bobbin-thread. The morefavorablelead of the bobbin-thread 18' relative to-wthebobbin-thread pull-off flange 14 insures. a greater accuracy in-- the amount of' bobbin-thread made available fbreach stitch: If the amount of bobbinthread available is not enough, it is necessary to steal thread from the bobbin 7 when the stitch is set which, of course, adversely affects the quality of the stitch. Because of the thread-eye 24, the lead of the bobbinthread is very close to the path of motion of the bobbin-thread pull-off flange 14 so that there is a very sharp angle in the lead about the flange 14 to the work. In comparison, the lead of the bobbin-thread in the device of Figs. 7l0 is from a point spaced from the path of travel of the flange 14 which results in only a gentle angle in the lead of the bobbin-thread about the flange 14 toward the work.

Another advantage derived by the present invention is that the operation of the rotary hook embodying the same is snappy. With a rotary hook, at cast-01f it is necessary that there be a minimum of looseness in the needle-thread or, in other words, that the thread be nicely snubbed about the hook elements, so that the thread will quickly move off the beak 3 of the hook onto the loop-controlling tail 11. If this action is sluggish as when there is looseness in the needle-thread, there is a tendency for the thread to become jammed between the bearing rib 4 and the raceway in the hook-body 1. A certain amount of control over this condition is exercised by the present device. In the hook of Figs.

7-1.0, the. needlevthreads. move substantially laterally across the front and rear. surfaces. of bobbin-case 6 and carrier 5.. Onthe other hand, with the bobbin-thread lead anchored by the threadaeye '24,. it will serve as a fulcrum. about which the needle-thread may pivot as the loop passes over the bobbin-thread mass. There is a certain amount. of take-up action. on. the needle-thread because the paththat it must: travel. has been made longer by bending it about the bobbin-thread limb. In addition, the critical portion of the cycle insofar as transferring the loop from the beak 3 to the tail 11 is concerned occurs 'at'a po'iht almost diametrically opposite to the point of contact of. the needle and bobbin-threads. Thus, at cast-off, considering the point of contact of the threads. as thep'ivot point, the loop is pivoting about a diameterand' there is. consequently little thread given up at this portion of the. cycle and there is little loose thread in the system. The needle-thread loop is, relatively speaking, snubbed about the hook beak 3 so that the loop will be snapped from the beak 3 to the tail I1. A still further advantage ofthis invention is that the bobbin thread 20 emerges from the thread-eye 24 substantially tangentially to the bobbin-case 6 so that any pull exerted upon the bobbin-thread will tend to rotate the bobbin-carrier in a counterclockwise direction as seen in' Fig. 2; As will be evident, the feeding mechanism of the machine isoperative at that portion of the cycle illustrated in Fig. 4 which thus-pulls the bobbin-thread and thereby: opens a gap between the notch 25 and the rotationrestraining finger topermit escape of the thread loop from the hook.

Numerous alterations of the structure herein disclosed willsuggest themselves to those skilled. in the art. However, it is to be; understood that the present disclosure relates to a preferred embodiment'of my invention which is for purposes; of illustration only and: not to be construed as a limitation ofthe' invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims;

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine'having a work-supporting surface andstitching. mechanism including a reciprocatory needle adapted to be" actuated to defiine a path of needle reciprocation extending through said work-supporting surface and a rotary hook disposed upon the opposite side of said Work-supporting surface from said needle and adapted to cooperate with said needle in the formationof two-thread lock-stitches, said hook comprising a cup-shaped body having an internal circular raceway, a stationary bobbin-case-carrier having a cylindrical sidewall and a bearing rib on the periphery of said side-wall, said bobbin-case-carrier being mounted in said rotary hook with said bearing rib journaled in said raceway for rotation of said hook relatively to said bobbin-case-carrier, said bobbin-case-carrier being adapted to receive a bobbincase and a bobbin mounted therein, said bobbin-case having an aperture through which a bobbin-thread is adapted to emerge, and means for directing the bobbin-thread from said aperture toward said working-supporting surface and relatively to the path of needle reciprocation to prevent orientation of the bobbin-thread relatively to the path of needle reciprocation resulting in hitch-stitches, said means comprising athread-eye extending through the side-wall of said bobbin-case-carrier and opening on the periphery thereof at a point disposed laterally of the path of needle reciprocation with respect to the axis of said hook and spaced therefrom on the cast-on side of said bobbincase-carrier.

2. In a sewing machine in accordance with claim 1 in which said bobbin-case-carrier has an open-ended threading slot in the side-wall thereof extending inwardly from the free edge thereof and communicating with said thread-eye.

ing rib on the periphery of said side-wall for mounting said bobbin-case-carrier within a rotary hook for rotation of the hook relatively thereto, said bobbin-case-carrier having a needle clearance aperture in the side-wall thereof to provide for penetration of said side-wall by a reciprocatory sewing needle the operation of which defines a path of needle reciprocation relatively to said bobbincase-carrier, said bobbin-case-carrier having a thread-eye through said side-wall and opening on the periphery thereof at a point disposed substantially in a plane normal to the axis of said bobbin-case-carrier and through said needle clearance aperture and spaced angularly from said needle clearance aperture on the cast-on side of said bobbin-case-carrier for directing a bobbin-thread from said bobbin-case-carrier relatively to the path of needle reciprocation to prevent orientation of the bobbin-thread relatively to the path of needle reciprocation resulting in hitch-stitching.

4. A bobbin-case-carrier for a rotary hook of a sewing machine and for receiving a thread-carrying bobbin, said bobbin-case-carrier comprising a cylindrical side-wall, having a free front edge terminating on the cast-01f side of said bobbin-case-carrier in a loop-controlling flange, a bearing rib on the periphery of said side-Wall for mounting said bobbin-case-carrier within a rotary hook for rotation of the hook relatively thereto, said loopcontrolling flange having a notch therein for receiving a rotation-restraining means, said bobbin-case-carrier haviug a needle clearance aperture in the side-wall therefor rearwardly of said loop-controlling flange and adjacent to said rotation-restraining notch to provide for penetration of said side-wall by a reciprocatory sewing needle the operation of which defines a path of needle reciprocation relatively to said bobbin-case-carrier, said bobbincase-carrier having a thread-eye through said side-wall and opening on the periphery thereof at a point disposed substantially in a plane normal to the axis of said bobbincase-carrier and through said needle clearance aperture and spaced angularly from said needle clearance aperture on the cast-on side of said bobbin-case-carrier for directing a bobbin-thread from said bobbin-case-carrier relatively to the path of needle reciprocation to prevent orientation of the bobbin-thread relatively to the path of needle reciprocation resulting in hitch-stitching.

5. A bobbin-case-carrier in accordance with claim 4 in which said sloop-controlling flange extends beyond said needle clearance aperture and said thread-eye onto the cast-on side of said bobbin-case-carrier, and said thread-eye is formed in said flange.

6. A bobbin-case-carrier in accordance with claim 4 in which said bobbin-case-carrier has an open-ended threading slot in the side-wall thereof extending inwardly from the free edge thereof and communicating with said thread-eye.

7. In a sewing machine having a work-supporting surface, feeding mechanism for advancing work over said work-supporting surface and thereby defining a line of feed, and stitching mechanism including a pair of parallel reciprocatoory needles adapted to be actuated to define parallel paths of needle reciprocation extending through said work-supporting surface and a rotary hook disposed upon the opposite side of said work-supporting surface from said needles and arranged upon an axis parallel to said line of feed for cooperation with said needles in the formation of three-thread lock-stitches, said hook comprising a cup-shaped body having an internal raceway, a stationary bobbin-case-carrier having 'a cylindrical side, wall and a bearing rib on the periphery of said side-wall, said bobbin-case-carrier being mounted in said rotary hook with said bearing rib journaled in said raceway for rotation of said hook relatively to said bobbin-case-carrier, said bobbin-case-carrier being adapted to receive a bobbin-case and a bobbin mounted therein, said bobbincase having an aperture through which a bobbin-thread is adapted to emerge, and means for directing the bobbinthread from said aperture toward said work-supporting surface and relatively to the paths of needle reciprocation to prevent orientation of the bobbin-thread relatively to the path of needle reciprocation of both of said needles resulting in hitch-stitches, said means comprising a threadeye extending through the side-wall of said bobbin-casecarrier and opening on the periphery thereof at a point disposed laterally of the paths of needle reciprocation of said needles with respect to the axis of said hook and spaced therefrom on the cast-on side of said bobbincase-carrier.

References Cited in the file of this patent UNITED STATES PATENTS Kessler June 29, 1937 

